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The 12C(gamma,NN) reaction studied over a wide kinematic range

Watts, D.P. et al. (2000) The 12C(gamma,NN) reaction studied over a wide kinematic range. Physical Review C, 62 (1). 014616-1-014616-15. ISSN 0556-2813 (doi:10.1103/PhysRevC.62.014616)

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Publisher's URL: http://dx.doi.org/10.1103/PhysRevC.62.014616

Abstract

The12C( gamma,np) and 12C( gamma,pp) reactions have been studied using the Glasgow photon tagging spectrometer at the Mainz MAMI electron microtron for E gamma = 150-700 MeV over a kinematic range which extends well beyond the approximately back-to-back detector arrangements of previous work. For 12C(gamma,np) the general trends of the missing energy distributions are reproduced over a wide range of kinematics and photon energies by the theory developed by the Valencia group. The corresponding 12C(gamma,PP) channel is overestimated by a factor of similar to 3. Detailed comparisons of the experimental data with a Monte Carlo simulation of the direct 2N knockout process provide the first evidence above the Delta resonance for direct 2N knockout and show that this process dominates the 12C(gamma,np) reaction at low missing energies up to E gamma similar to 700 MeV. The 12C(gamma,pp) reaction is somewhat less well described by the Monte Carlo simulation. A possible explanation of the observed discrepancies within a direct 2N framework is presented. At high recoil momenta both 2N reaction channels exhibit an excess yield compared to the Monte Carlo prediction of direct 2N knockout. The excess yield in this region is compared with the predicted effects of short-range correlations and with the predicted contributions due to other reaction mechanisms.

Item Type:Article
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:McGeorge, Dr John and Branford, Prof Derek and MacGregor, Dr I and Annand, Dr John and Kellie, Dr James and Watts, Dr Daniel and Owens, Prof Robert
Authors: Watts, D.P., MacGregor, I.J.D., Ahrens, J., Annand, J.R.M., Beck, R., Branford, D., Grabmayr, P., Hall, S.J., Harty, P.D., Hehl, T., Kellie, J.D., Lamparter, T., Liang, M., MacKenzie, J.A., McAllister, S.J., McGeorge, J.C., Owens, R.O., Sauer, M., Schneider, R., Wagner, G.J., and Yau, T.T.H.
Subjects:Q Science > QC Physics
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review C
ISSN:0556-2813
ISSN (Online):1089-490X

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